 |
PDBsum entry 3ibr
|
|
|
|
References listed in PDB file
|
 |
|
Key reference
|
|
|
Title
|
|
Conformational differences between the pfr and pr states in pseudomonas aeruginosa bacteriophytochrome.
|
|
|
Authors
|
|
X.Yang,
J.Kuk,
K.Moffat.
|
|
|
Ref.
|
|
Proc Natl Acad Sci U S A, 2009,
106,
15639-15644.
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
Phytochromes are red-light photoreceptors that regulate light responses in
plants, fungi, and bacteria by means of reversible photoconversion between red
(Pr) and far-red (Pfr) light-absorbing states. Here, we report the crystal
structure of the Q188L mutant of Pseudomonas aeruginosa bacteriophytochrome
(PaBphP) photosensory core module, which exhibits altered photoconversion
behavior and different crystal packing from wild type. We observe two distinct
chromophore conformations in the Q188L crystal structure that we identify with
the Pfr and Pr states. The Pr/Pfr compositions, varying from crystal to crystal,
seem to correlate with light conditions under which the Q188L crystals are
cryoprotected. We also compare all known Pr and Pfr structures. Using
site-directed mutagenesis, we identify residues that are involved in stabilizing
the 15Ea (Pfr) and 15Za (Pr) configurations of the biliverdin chromophore.
Specifically, Ser-261 appears to be essential to form a stable Pr state in
PaBphP, possibly by means of its interaction with the propionate group of ring
C. We propose a "flip-and-rotate" model that summarizes the major conformational
differences between the Pr and Pfr states of the chromophore and its binding
pocket.
|
|
|
|
|
|
|
